JPH10206868A - Color liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a display with high luminance by forming a conductive black matrix layer, a nonconductive color filter, a protection film which has an opening formed, and a common transparent electrode on the liquid-crystal side surface of one transparent substrate. SOLUTION: A filter substrate FILSUB has a black matrix layer BM fold of a conductive material on the surface of its transparent substrate on the side of liquid crystal. In each pixel area, a color filter FIL having a color specified for the pixel area is formed of, for example, a dyed resin film. On their top surfaces, protection films PAS are formed of, for example, silicon nitride films and have opening parts formed so that their center parts except the peripheral part of the color filters FIL are exposed. Then, the common electrode ITO' formed of a transparent electrode common to the respective pixel areas is formed on the protection films PAS and the top surfaces of the color filters FIL exposed in their opening parts and on its top surface, an orientation film is formed which prescribes the orientation of the liquid crystal LC.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display, and more particularly, to a liquid crystal display for color display.

[0002]

2. Description of the Related Art A liquid crystal display panel in a liquid crystal display device for color display includes a pair of transparent substrates opposed to each other with a liquid crystal interposed therebetween, each of which has a predetermined area in each pixel region on a liquid crystal side of one of the transparent substrates. Is characterized in that a color filter having the following color is formed. Hereinafter, the transparent substrate on which the color filters are formed as described above may be referred to as a filter substrate in this specification.

More specifically, for example, in the case of a liquid crystal display device called an active matrix type, scanning signals extending in the x direction and juxtaposed in the y direction are provided on the surface of the other transparent substrate on the liquid crystal side. And a video signal line which is insulated from the scanning signal line, extends in the y direction, and is juxtaposed in the x direction.
Each rectangular area surrounded by these signal lines is configured as a pixel area.

To each of these pixel regions, a thin film transistor (TFT) turned on by the supply of a scanning signal from a scanning signal line, and a video signal supplied from a video signal line via the turned on thin film transistor are applied. And a transparent pixel electrode. Hereinafter, the transparent substrate on which the thin film transistor is formed as described above may be referred to as a TFT substrate in this specification.

The liquid crystal side surface of the filter substrate, which is disposed to face the TFT substrate, is configured such that a region facing the pixel region of the TFT substrate is formed as a pixel region. A matrix layer is formed. This is to improve the contrast of each pixel. A color filter of a predetermined color is formed in a pixel region surrounded by the black matrix layer.

Further, a protective film is formed over the entire area so as to cover such a black matrix layer and a color filter, and a transparent common electrode common to each pixel region is formed on the upper surface of the protective film.

[0007]

The liquid crystal display device having such a configuration controls the light transmittance of the liquid crystal interposed between the common electrode and the pixel electrode in accordance with the potential difference applied between the electrodes. Therefore, it is desired to improve the light transmittance by reducing the layer structure at least in the pixel region as much as possible.

[0008] If the light transmittance can be improved in this manner, high-luminance display can be performed without increasing the power of the backlight disposed on the back of the liquid crystal display panel.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a liquid crystal display device capable of displaying a high luminance.

[0010]

In order to achieve the above object, a liquid crystal display device according to the present invention basically comprises:
Of a pair of transparent substrates opposed to each other via a liquid crystal, a conductive black matrix layer bordering at least one side of each pixel region is formed on a liquid crystal side surface of one of the transparent substrates, and formed on each pixel region. A non-conductive color filter, a protective film covering the black matrix layer and having an opening for exposing the color filter, and an upper surface of the protective film and the color film, each pixel region or a part thereof. A transparent electrode common to the pixel region is formed.

In the liquid crystal display device thus configured, since no protective film is formed in each pixel region, light absorbed by the protective film is reduced, and light transmittance is reduced. Can be improved.

Although it is conceivable to improve the light transmittance by not forming this protective film at all, in the present invention, in such a case, a black matrix layer made of a conductive material is used. The black matrix layer is prevented from being damaged by so-called electrolytic corrosion caused by direct contact of the dissimilar metal with the common electrode.

That is, a protection film is left in a formation region of a black matrix layer which does not substantially function as a pixel region so as to cover the black matrix layer, and the protection film is directly connected to a common electrode formed on the protection film. The contact can be avoided.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the color liquid crystal display device according to the present invention will be described below with reference to the drawings.

[Embodiment 1] FIGS. 1 to 3 show an embodiment in which the present invention is applied to a so-called active matrix type color liquid crystal display device.

The entire TFT substrate configuration First, FIG. 2, one of the transparent substrate of the pair of transparent substrates which are arranged to face each other through a liquid crystal, the liquid crystal side surface of the transparent substrate, referred to as a so-called TFT substrate TFTSUB FIG. 3 is a plan view showing a configuration. Although the other transparent substrate opposed to the TFT substrate TFTSUB is not shown, it is arranged opposite to the one-dot chain line as an outer contour in the figure, and a common electrode (common to each pixel) is provided on its liquid crystal side surface. A transparent electrode is formed, and a color filter is formed for each corresponding pixel region.

On the surface of such a TFT substrate TFTSUB, first, scanning signal lines G0 to Gi to Gn extending in the x direction in the drawing and arranged in parallel in the y direction are formed. At one end (left side in the figure) of each of the scanning signal lines G0 to Gi to Gn, a terminal portion GPAD is provided at a side portion of the TFT substrate TFTSUB. These terminals GPA
D is a terminal unit connected to, for example, an external drive circuit for supplying a scanning signal.

Each of the scanning signal lines G0 to Gi to
Video signal wirings D1 to Di to Dm are formed extending in the y direction in the drawing and juxtaposed in the x direction via Gn and an interlayer insulating film.

At one end (upper side in the figure) of each of these video signal wirings D1 to Dj to Dm, a TFT substrate TFTS
A terminal portion DPAD is provided at a side portion of the UB.
Each of these terminal portions DPAD is a terminal portion connected to, for example, an external drive circuit for supplying a video signal.

Each of the regions surrounded by each of the scanning signal lines G0 to Gi to Gn and each of the video signal lines D0 to Di to Dm constitutes a pixel region.
1), (1, 2), ..., (2, 1), (2, 2), ...,
A set of (m, n) constitutes a display unit (a part surrounded by a dotted line in the figure). The detailed configuration of each pixel region in the display unit will be described later.

The structure of each pixel region These pixel regions (1, 1), (1, 1),.
Each of n) is configured as shown in FIG. FIG. 3B is a cross-sectional view taken along the line IIIb-IIIb in FIG. Hereinafter, each component will be described in the order of the manufacturing process.

In the figure, first, a TFT substrate TFTS
Scan signal lines Gi and Gi _-1 are formed on the UB so as to extend in the x direction in the drawing and to be separated from each other. The material of the scanning signal lines Gi and Gi _-1 is not particularly limited, but in this embodiment, for example, an alloy layer of Cr and Mo is used.

The vicinity of the scanning signal wiring Gi (the lower scanning signal wiring in the figure) is a region where a so-called inverted staggered thin film transistor TFTT is formed.
At the time of forming the scanning signal wiring Gi, a part thereof is extended to the region so that the gate electrode 26G of the thin film transistor TFT is formed.

Then, a silicon nitride film to be a gate insulating film 26I and a semiconductor layer 26S made of amorphous Si, for example, are sequentially covered so as to cover the gate electrode 26G.
Is formed.

By forming the drain electrode Ed and the source electrode Es on the upper surface of the semiconductor layer 26S apart from each other, the thin film transistor TFT is formed. These electrodes Ed and Es are connected to the video signal wiring Dj. Are formed simultaneously with the formation of

That is, the video signal wiring Dj is, for example, C
A drain electrode Ed is formed by being formed of an alloy layer of r and Mo, a part of which is formed to extend, and at the same time, a source electrode Es is formed to achieve conduction with a pixel electrode ITO described later. Have been.

In order to insulate the video signal wiring Dj from the scanning signal wiring Gi and the like, an interlayer insulating film formed simultaneously with the above-described laminated body of the silicon nitride film and the semiconductor layer at the intersection thereof is formed. It is formed on the film 36.

In this embodiment, the semiconductor layer 26
For example, N for making ohmic contact with the drain electrode Ed and the source electrode Es is formed on the entire surface of S.
Forming a contact layer doped with a p-type impurity layer, forming the electrodes Ed and Es, and then forming the electrodes Ed and Es.
The contact layer is etched using the mask as a mask, so that the contact layer is left under the electrodes Ed and Es.

A protective film 38 made of, for example, a silicon nitride film is formed on the entire upper surface of the TFT substrate TFTSUB thus processed. This is for avoiding direct contact between the thin film transistor TFT and the liquid crystal to prevent deterioration of the characteristics of the thin film transistor TFT.

Further, a pixel electrode ITO is formed on the upper surface of the protective film 38 by a transparent conductive material made of, for example, ITO (Indium-Tin-Oxide), and a part thereof is formed by a contact formed on the lower protective film 38. It is connected to the source electrode Es through a hole TH.

By forming such a pixel electrode ITO on the protective film 38, the video signal lines Dj, Dj
Since there is no fear of electrical contact with _{j + 1} , the area can be increased and the so-called aperture ratio can be improved.

A part of the pixel electrode ITO is extended, and another video signal wiring Gi _-1 adjacent to the video signal wiring Gi for turning on the thin film transistor TFT in the drawing.
To form an additional capacitive element Cadd using the protective film 38 as a dielectric film. This additional capacitance element Cadd is a thin film transistor T
This is provided for storing a video signal in the pixel electrode ITO for a long time when the FT is turned off.

The diagram 1 of a filter substrate, a cross-sectional view taken along line I-I of FIG. 3, the TF
This TFT substrate TFTS together with the T substrate TFTSUB
A filter substrate T that is arranged to face the UB via the liquid crystal LC
ILSUB is also shown.

In the figure, a filter substrate FILSUB
First, a black matrix layer BM is formed on the liquid crystal side surface of the transparent substrate. The black matrix layer BM is made of, for example, Cr (chromium) or C
It is made of a resin containing (carbon) or the like, and is made of a conductive material.

The black matrix layer BM may have, as a planar pattern, a grid-like shape surrounding the periphery of each pixel region. It may be a stripe shape formed in a region extending (when viewed in a plane).

In any case, the black matrix layer BM is formed to improve the contrast of each pixel, and its shape is not limited as long as it has the function.

In each pixel region, a color filter FIL having a color specified by the pixel region is formed by, for example, a dyed resin film. The color filter FIL is formed so as to be separated from the adjacent color filter FIL of another color, and the periphery thereof is formed so as to overlap the black matrix layer BM.

Further, a protective film PAS made of, for example, a silicon nitride film is formed on the upper surfaces of the black matrix layer BM and the color filter FIL. In this embodiment, the protective film PAS is
An opening is formed in which a central portion excluding a peripheral portion of the color filter FIL is exposed.

That is, by adopting a configuration in which the protective film PAS is not formed substantially in the pixel region,
The light transmittance is prevented from being reduced by the presence of the protective film PAS.

By completely covering the black matrix layer BM at least in a region where the black matrix layer BM is formed, the protective film PAS can avoid direct contact with the common electrode ITO 'described below. It has a configuration. This is because when the conductive black matrix layer BM and the common electrode ITO ′ are formed in contact with each other, electrolytic corrosion occurs between the dissimilar metals and the black matrix layer BM is prevented from being corroded.

The protective film PAS and the color filter FIL exposed from the opening of the protective film PAS
A common electrode ITO ′ made of a transparent electrode common to each pixel region is formed on the upper surface of the pixel electrode, and an alignment film (not shown) for defining the alignment of the liquid crystal LC is formed on the upper surface of the common electrode ITO ′. I have.

In the liquid crystal display device thus configured, since the protective film PAS is not formed in each pixel region, light absorbed by the protective film PAS is reduced, and light transmission is reduced. Characteristics can be improved.

It is conceivable to improve the light transmittance by not forming this protective film PAS at all. In the present invention, however, in this case, the black matrix layer made of a conductive material is used. A so-called electrolytic corrosion action due to direct contact between the BM and the dissimilar metal between the common electrode ITO ′ (in this case, the liquid crystal acts as an electrolyte)
Thus, the black matrix layer BM is prevented from being damaged.

That is, in the formation region of the black matrix layer BM which does not substantially function as a pixel region, the protective film PA is formed so as to cover the black matrix layer BM.
The structure is such that S is left and direct contact with the common electrode ITO ′ formed on the protective film PAS can be avoided.

Embodiment 2 FIGS. 4 to 6 show an embodiment in which the present invention is applied to a so-called simple matrix type liquid crystal display device.

As shown in FIG. 4, a simple matrix type liquid crystal display device basically has a transparent substrate SUB1 having a transparent substrate SUB1 disposed on the liquid crystal side of one of the transparent substrates opposed to each other with the liquid crystal interposed therebetween. A display electrode 1 extending in the x direction and arranged in parallel in the y direction is provided.
A scanning electrode 2 extending in the direction and juxtaposed in the x direction, and a region (intersecting region) where the display electrode and the scanning electrode face each other is configured as a pixel region.

Then, the transparent substrate SU of the transparent substrate SUB1
A region not opposed to B2 is provided, and a display electrode terminal 1A for supplying a display signal to each display electrode 1 is formed in this region. The transparent substrate SUB of the transparent substrate SUB2
A scanning electrode terminal 2 </ b> A for supplying a scanning signal to each scanning electrode 2 is formed in this region that does not face 1.

Hereinafter, the structure on the transparent substrate side on which the display electrodes are formed and the structure on the transparent substrate side on which the scanning electrodes are formed will be described.

[0049] The block diagram 5 of the display electrode is formed transparent substrate side shows a cross-sectional view taken along line V-V in Fig 4, 6 4
1 is a sectional view taken along line VI-VI of FIG.

On the surface of the transparent substrate SUB1 on the liquid crystal side, display electrodes 1 extending in the x direction in the figure and juxtaposed in the y direction are formed. Is formed. As the electrode protective film 5, a material such as a silicon oxide film is selected.

An alignment film (not shown) for regulating the alignment of the liquid crystal LC is formed on the entire upper surface of the electrode protection film 5.
Are formed.

Structure on Transparent Substrate Side with Scan Electrodes Formed As shown in FIGS. 5 and 6, a black matrix layer BM is first formed on the liquid crystal side surface of the transparent substrate SUB2. The black matrix layer BM is made of, for example, a resin containing Cr (chromium) or C (carbon), and is a conductive material.

The black matrix layer B
M has a lattice-like pattern formed so as to surround each pixel region, that is, to surround a region where a scanning electrode 2 and the display electrode 1 described later intersect.

Further, the black matrix layer BM
Are formed in the pixel region surrounded by the color filters FIL dyed in a color corresponding to the pixel, and the peripheral portion of each color filter FIl is formed so as to overlap the black matrix layer BM.

Further, a protective film PAS made of, for example, a silicon nitride film is formed on the upper surfaces of the black matrix layer BM and the color filter FIL. This protective film PAS is particularly used in this embodiment.
An opening is formed in which a central portion excluding a peripheral portion of the color filter FIL is exposed.

That is, by adopting a configuration in which the protective film PAS is not formed substantially in the pixel region,
The light transmittance is prevented from being reduced by the presence of the protective film PAS.

The protective film PAS completely covers the black matrix layer BM at least in a region where the black matrix layer BM is formed, so that direct contact with the scanning electrode 2 described below can be avoided. It has become. This is because when the conductive black matrix layer BM and the scan electrode 2 are formed in contact with each other, electrolytic corrosion occurs between the dissimilar metals and the black matrix layer BM is prevented from being corroded.

Then, the protective film PAS and the color filter FIL exposed from the opening of the protective film PAS
A scanning electrode 2 made of a transparent electrode common to each pixel region is formed on the upper surface of the pixel.
An alignment film (not shown) that defines the alignment of the semiconductor device is formed.

Since the liquid crystal display device thus configured does not have the protective film PAS formed in each pixel region, the amount of light absorbed by the protective film PAS is reduced, and light transmission is reduced. Characteristics can be improved.

It is conceivable to improve the light transmittance by not forming this protective film PAS at all. In the present invention, however, in this case, the black matrix layer made of a conductive material is used. The black matrix layer BM is prevented from being damaged by so-called electrolytic corrosion caused by direct contact between the BM and the dissimilar metal of the scanning electrode 2.

That is, in the formation region of the black matrix layer BM which does not substantially function as a pixel region, the protective film PA is formed so as to cover the black matrix layer BM.
With S left, direct contact with the scanning electrode 2 formed on the protective film PAS can be avoided.

In the above-described embodiment, a color liquid crystal display device having a typical configuration has been described.
It goes without saying that the present invention can be applied to a color liquid crystal display device having a configuration other than that of this embodiment.

[0063]

As is apparent from the above description,
According to the liquid crystal display device for color according to the present invention, since the light transmittance can be improved, a display with high luminance can be achieved.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a main part of an embodiment of a color liquid crystal display device according to the present invention.

FIG. 2 is a schematic plan view showing one embodiment of a TFT substrate of a color liquid crystal display device according to the present invention.

FIG. 3 is a configuration diagram showing one embodiment of a pixel region on a TFT substrate of a color liquid crystal display device according to the present invention.

FIG. 4 is a schematic plan view showing another embodiment of the color liquid crystal display device according to the present invention.

FIG. 5 is a sectional view taken along line VV in FIG. 4;

FIG. 6 is a sectional view taken along line VI-VI of FIG.

[Explanation of symbols]

FIL ... filter substrate, BM ... black matrix layer, FIL ... color filter, ITO '... common electrode, 2 ... scanning electrode.

 ──────────────────────────────────────────────────の Continued on front page (72) Inventor Yoshiki Watanabe 3681 Hayano, Mobara-shi, Chiba Hitachi Device Engineering Co., Ltd. (72) Inventor Junichi Owada 3300 Hayano, Mobara-shi, Chiba Hitachi, Ltd.

Claims (3)

[Claims] 1. A conductive black matrix layer bordering at least one side of each pixel region on a liquid crystal side surface of one of a pair of transparent substrates disposed to face each other with a liquid crystal therebetween. A non-conductive color filter formed in each pixel region, a protective film having an opening for covering the black matrix layer and exposing the color filter, and a protective film formed on an upper surface of the protective film and the color film. A color liquid crystal display device, wherein a transparent electrode common to a pixel region or a partial pixel region is formed. 2. The color liquid crystal display device according to claim 1, wherein the common transparent electrode is applied to an active matrix type liquid crystal display device and is formed over the entire area of each pixel region. 3. A liquid crystal display device of a simple matrix type, wherein the common transparent electrode is formed for each row or column over each pixel region arranged in a row direction or a column direction. 2. A color liquid crystal display device according to claim 1.